The disclosure relates generally to fiber optic connectors, and more particularly to removing polymer coatings overlaying optical fibers, which may be used when preparing the optical fibers for attachment in ferrules of the fiber optic connectors.
Benefits of optical fibers include extremely wide bandwidth and low noise operation. In cases where high bandwidth is required between two interconnection locations, fiber optic cables having fiber optic connectors may be used to communicate information between these locations. The fiber optic connectors may be used to conveniently connect and disconnect the fiber optic cables from the interconnection locations, for example, to facilitate maintenance and upgrades.
Fiber optic connectors include a ferrule assembly having a ferrule. The ferrule has several purposes. The ferrule includes an internal pathway, called a ferrule bore, through which an optical fiber is supported and protected. The ferrule bore also includes an opening at an end face of the ferrule. The opening is where an optical core of an end portion of the optical fiber may be located to be aligned to an end portion of another optical fiber of a complementary connector. The optical core may be as small as eight (8) microns, such that the end portions of the optical fibers need to be precisely aligned to establish an optical connection.
The optical fibers typically include a glass fiber (e.g., cladding and optical core) surrounded by a protective polymer coating, which is removed from an end portion of an optical fiber prior to being disposed within the ferrule bore of the ferrule. This is because the polymer coatings do not currently have the robust mechanical properties necessary to be attached to the ferrule bore to withstand the cyclical tension experienced during the use of the fiber optic optic connector over time without displacement creep or breakage. Also, the glass fiber of the optical fiber is not centered within the polymer coating with sufficient accuracy to permit the glass fiber to be precisely located within the ferrule bore without removing the coating. For at least these reasons, the coating is removed from the end portion of the optical fiber prior to being disposed in a ferrule.
Various methods are available to remove the coating from an optical fiber, including hot gas stripping, mechanical stripping, chemical stripping, and laser stripping. All of these methods have drawbacks. Hot-gas stripping uses a heated jet of gas (e.g., nitrogen or air) to melt and remove the coating, but considerable debris is often created. The hot-gas stripping approach may also incompletely evaporate the coating, and/or may overheat heat-sensitive materials in close proximity to the fiber core.
Mechanical stripping of optical fibers includes physically removing the coating material from the glass fiber with a semi-sharp edge of a stripping blade made of a metal or a polymer, as may be similar to mechanical stripping of electrical wires. However, mechanical stripping may have issues because the optical fiber may be damaged, and stripping blades are needed that require time-consuming inspection and replacement procedures. Chemical stripping of optical fibers uses chemicals to dissolve the coating from the glass portion of the optical fiber, but these chemicals require extensive procedures to protect the environment and safety measures to protect personnel.
Laser stripping utilizes one or more laser beams to strip the coating from glass optical fibers typically using a vaporization or ablation process as laser energy is absorbed by the polymer coatings. In order to remove the coatings around a circumference of the optical fiber the laser energy must be distributed around the circumference which, typically requires added complexity and cost. For example, complex three-dimensional mirrors may be utilized, or the optical fiber may be moved relative to a laser beam using specialized equipment.
In addition, once coating is removed from an end portion of an optical fiber using any of the above-mentioned methods, the optical fiber is vulnerable to damage. A stripped portion of an optical fiber may be damaged merely by being in contact with particulates which could scratch or damage an exterior surface of the optical fiber where coating has been removed. Any coating stripping process completed prior to insertion of the optical fiber into a ferrule must be managed carefully so that the stripped portion of the optical fiber is not damaged prior to being protected within the ferrule.
What is desired is a more cost-effective and efficient method to prepare an end portion of an optical fiber for terminating into a ferrule so that the end portion is coupled to the ferrule and the coating of the end portion of the optical fiber is removed or substantially removed. The method and associated equipment should remove the coating from the end portion of the optical fiber while minimizing damage to the optical fiber. The method should also be efficient, inexpensive, and not require unsafe chemicals.